Fluorescent radiation from Mo anode tubes is commonly used for film mammography. The quasimonoenergetic radiation at low energy (17-20 KeV) produces good subject contrast. However this low energy radiation does not penetrate well so it produces a high dose. Recent results have indicated that radiation of slightly higher energy (20-20 KeV) might provide adequate contrast, thus permitting imaging at much lower dose. This study will investigate the fabrication of several "transmolybdenum" (i.e. Z greater than ZMo) anodes for use in mammography. A demountable x-ray tube has been fabricated which will permit the interchange of several different anode materials. Rhodium and palladium anodes have been constructed by depositing thin film on graphite and copper substrates. Other anodes will be studied. A Si(Li) spectrometer interfaced to a minicomputer will be used to analyze the spectral distribution. Techniques can be adjusted to provide beams of similar spectral purity from the different anodes. This will permit a study of the effect of energy on subject and radiographic contrast. Thermal loading presents the major problem in these new anodes. The data gathered from the work above should indicate which energies are most promising for mammography. Solutions for the specific elements will be sought. Thermal aging of the demountable anodes can be studied microscopically. Since the anodes can be easily replaced, destructive testing can also be done to determine operating limits. The final goal is to produce a new fluorescent anode tube for mammography with clinically useful output.